1. Mineral Separation
Many important metal ores are sulfides. Significant examples include; argentite (silver sulfide), galena (lead sulfide), molybdenite (molybdenum sulfide), pentlandite (nickel sulfide]), realgar (arsenic sulfide), and stibnite (antimony), sphalerite (zinc sulfide), and pyrite (iron disulfide), and chalcopyrite and bornite (iron-copper sulfide). Vaughan, D. J. Craig, J. R. 1978
Mined base metal sulfide ore generally contains around 0.5% to 15% of valuable metal, with the remainder being waste. Separating the valuable metal from the waste is usually carried out by grinding an ore-water mix in a mill with steel balls or rods. The grind slice varies but the particles are generally in the size range of 1-120 microns. The metal sulfides are separated by adding chemicals and floating the valuable metal sulfides to the surface in a froth phase and the waste remains in the slurry and reports to the tailings. This flotation separation process is limited in its efficiency.
2. Selective Recovery of Fine Minerals
In the separation of valuable minerals from an ore, whether by flotation separation or gravity separation or some other method, it has been found that fine minerals, those less than 38 μm and more preferably less than 20 μm are difficult to recover efficiently.
An invention that substantially improves the magnetization of the slurry so that there is an increase in the recovery of these <20 μm minerals or that would magnetise the slurry more efficiently or at a lower cost would be very advantageous.
Another problem that can arise in the removal of the magnetic material from the magnetic source is that removing the magnetic source from the flow-stream and washing the accumulated magnetic material from the magnetic housing is not sufficient to remove all the accumulated material. This is because the accumulated material can be iron based material that in the oxidising aqueous environment of the flowstream slowly oxidizes (rusts) and can form a crust on the magnetic source housing. This oxidized iron crust needs to be disturbed or wiped in order for it to be removed to the slurry flowstream. For this reason a combined wiping and flowstream washing is required to remove all the accumulated magnetic material from the magnetic source.
It is postulated that any build-up of accumulated magnetised material on the magnetic source increases the distance between the magnetic source and the flowstream thus reducing the magnitude of the magnetic induction to the flowstream.
The requirement to mechanically move the magnetic source in and out of the flowstream requires that in the design of the piston magnetic source tolerances are required between the piston and housing. These tolerances increase the distance between the magnetic source and the slurry and so reduce the magnetic induction in the slurry.
It is postulated that in the magnetization of flotation slurry to selectively aggregate the paramagnetic minerals there may be an advantage if the magnetic source could remain in a fixed position in the magnetic source housing in the slurry flowstream. The advantages may be:    1. If the magnet remains in the flowstream, then the slurry is being continuously magnetised.    2. If the magnets remain stationary there is no limit to the mass of the magnets and allows for stronger magnetic fields since they are fixed and not being moved and so reduces the mechanical complexity of deactivating the magnetic source    3. If the magnets remain stationary and the mechanical complexity of deactivating the magnets is reduced then different materials can be used in the fabrication of the magnetic housing allowing closer proximity between the magnet and the flowstream, allowing for stronger magnetic induction in the slurry    4. It allows much closer proximity between the magnet and the flowstream and results in higher average magnetic inductions in the flowstream because no tolerance is required for the mechanical movement of the magnet    5. Because a heavy magnet is not being moved in and out of the flowstream then lower energy consumption is required and also lower maintenance.    6. The magnetic source can be cleaned more rapidly because only a wiper or series of wipers and not the massive magnet is moved, thereby, maintaining a stronger magnetic induction over a longer period of time    7. The speed of wiper movement to dislodge the ferromagnetic build-up can be varied depending on the amount of strongly magnetic material in the slurry, typically from 4 meters/minute to 0.5 meters/minute.    8. The combination of wipers and moving flowstream is more effective in removing the ferromagnetic build-up because of the physical wiping, instead of relying on washing alone while the magnet is deactivated    9. Because the magnet is maintained in the slurry and not removed from the slurry there is no exposure to personnel, equipment or tools from the magnetic induction, which is a safety consideration.